The present invention generally relates to a transporting apparatus and, more particularly, to a belt for belt turn conveyors.
Belt turn conveyors are used to provide turns, for example turns of 30xc2x0, 45xc2x0, 60xc2x0, 90xc2x0, and 180xc2x0, in a conveyor system. The belt turn conveyors are positioned between and interconnect the flow of generally straight conveyor sections to form a bend or curve in the conveyor system. A conventional belt turn conveyor typically includes a frame which supports a pair of conical shaped pulleys positioned at each end of the frame and a continuous belt which extends over and between the pulleys. In order to provide uniform contact with the rollers across the width of the belt, the belt has a smaller length at its inner radius and a longer length towards its outer radius.
The belt material forming both straight run belts and belts for curved conveyors is usually formed from a plurality of longitudinal and transverse fibers which extend through the belt material. Belts used on straight runs usually have strands or fibers running along the length of the belt and strands or fibers running transversely across the belt to provide strength to the belt. In this manner, the fibers are oriented along the direction of tension to minimize stretching. However, when belts are fabricated for belt turn conveyors, the belt material is cut from a piece of straight conveyor material (B) in the shape of the curve (see FIG. 10). For example, for a 90xc2x0 turn, the belt material is cut in a semi-circular annular section and folded over to form a 90xc2x0 closed loop. Thus, the orientation of the fibers remain generally parallel throughout the cross-section of the semi-circular shaped belt, but provide no uniformity along the curved longitudinal belt axis or, in other words, in the direction of pull or tension.
It has been found that belts for belt turn conveyors require relatively frequent replacement. Furthermore, it has been found that the wear along the belt is non-uniform. Stresses imposed on the belt by the radial forces generated at the curve tend to accelerate the wear of the belt material as compared to the wear of belts on straight run conveyors. As a result, the turn conveyor belt can become the weak link in a conveyor system.
Consequently, there is a need for an improved belt for belt turn conveyors that exhibits improved performance and longevity and, further, exhibits an increased capacity.
According to the present invention, a belt turn conveyor includes a continuous belt which exhibits improved longevity and/or increased capacity. The endless belt has a generally uniform stiffness along its length and width such that the forces associated with retaining the belt on the frame are more evenly distributed along the belt""s length.
In one form of the invention, a belt turn conveyor includes a frame and an endless belt which is rotationally supported by the frame. The endless belt is restrained in the frame to limit vertical and lateral movement of the belt with respect to the frame. The endless belt has a curved longitudinal axis and a plurality of fibers aligned along the curved longitudinal axis to provide directional strength to the belt in the tension direction. In this manner, the fibers of the endless belt are generally oriented to follow the curved path of the belt turn conveyor whereby the endless belt exhibits substantially uniform stiffness over its length and exhibits substantially reduced variations in forces where the belt is restrained on the frame.
In one aspect, the outer perimeter of the belt is restrained by the frame. For example, the outer perimeter of the belt may include at least one bearing assembly for engaging the frame to substantially retain the belt on the frame. Preferably, the outer perimeter of the belt includes a plurality of bearing assemblies, such as wheel assemblies, which engage the frame.
In another form of the invention, the endless belt comprises a plurality of interconnected belt segments. Each of the belt segments is interconnected to an abutting belt segment by either lacing or finger splicing, preferably by vulcanized finger splicing. For example, each belt segment may comprise a segment having an angle in a range of about a 5xc2x0 to 75xc2x0 per segment.
According to another form of the invention, a belt turn conveyor includes a frame with at least one bearing surface and an endless belt rotationally supported by the frame which extends along a curved path of the frame, with the endless belt having an inner perimeter and an outer perimeter. A plurality of bearing assemblies are secured to the outer perimeter of the endless belt, which engage the bearing surface of the frame for restraining movement of the endless belt on the frame. The endless belt has a curved longitudinal axis and a plurality of fibers generally aligned along the curved longitudinal axis to provide directional strength to the belt along the direction of tension whereby the endless belt exhibits substantially uniform stiffness over its length and exhibits substantially reduced variations in forces at its bearing assemblies.
In one aspect, the endless belt comprises a plurality of interconnected belt segments. In a further aspect, the interconnected segments are joined along an axis offset from a radial axis of the belt turn conveyor to thereby reduce the noise generated by the belt.
In other aspects, each of the segments includes a longitudinal axis and fibers generally aligned along the longitudinal axis, with the fibers of each segment generally aligned to follow the curved path of the frame. In further aspects, the fibers of each respective segment are aligned generally parallel to a tangent of a portion of the curved path corresponding to the respective segment.
In another form of the invention, an endless belt assembly for a belt turn conveyor includes an endless belt and at least one bearing assembly secured to the endless belt for engaging a bearing surface of a frame of a belt turn conveyor to retain the endless belt in the frame. The endless belt has a curved longitudinal axis coincident with the curved path of the belt turn conveyor and, further, includes a plurality of fibers generally aligned along the curved longitudinal axis of the endless belt whereby the endless belt exhibits substantially uniform stiffness over its longitudinal axis and exhibits substantially reduced forces at its outer perimeter thereby increasing the capacity of the endless belt or the longevity of the belt or both.
In one aspect, the bearing assembly comprises a plurality of bearing assemblies, for example, wheel assemblies. In another aspect, the endless belt comprises a plurality of interconnected belt segments. Preferably, each of the belt segments includes a longitudinal axis, and has a plurality of fibers which are aligned along the longitudinal axis of each belt segment. Each belt segment is interconnected with an abutting belt segment such that the fibers of each of the belt segments generally align along the curved longitudinal axis of the endless belt. In this manner, the belt of the present invention provides a curved belt which exhibits a more uniform stiffness along its length and, as a result, exhibits an increased capacity and/or longevity.
These and other objects, features, and advantages will become more apparent from a study of the drawings taken in conjunction with a review of the description which follows.